Method of making stretch yarns and fabrics



Jan. 30, 1968 .1. E. BROWN ET AL 3,365.771

METHOD OF MAKING STRETCH YARNS AND FABRICS Filed Aug. 26, 1965 2 Shanta-Sheet 1 MULTI-PLY YARN COMPRISING AT LEAST 65% REGENERATED CELLULOSE HAVING A WET MODULUS iq/den m 5%EXTENSION TREATQNG WITH SWELUNG AGENT EQUIVALENT TO AQUEOUS SOLUTION CONTAINING 5 TO 40% NOOH AND 1 TO 8% NoCl UNDER CONTROLLED TENSION POTENTIALLY STRETCHY YARN REVERSE TWIST STRETCHY, BULKY, IRREGULAR YARN James E Brown WW/0m Han/r Tay/or 8y me/raflorneys 1 Jan. 30, 1958 J. E. BROWN ET AL 3,365,771-

METHOD OF MAKING STRETCH YARNS AND FABRICS Filed Aug. 28,. 1965 2 Sheets-Sheet 2 i MULTl-PLY YARN cowmsmc AT tEAST 65% REGENERATED CELLULOSE AND HAVING A WET MODULUS OF g 1 den AT 5%EXTENS'ON TREATING WITH SWELLNG AGENT EQUIVALENT TO AQUEOUS SOLUTION CONTAINING 5T0 40% NOOH AND I TO 8% NOCI UNDER CONTROLLED TENSSON POTENTIALLY STRETCHY YARN REVERSE TWIST STRETCHY BULKY, \RREGULAR YARN PULL" OUT EXTENDED YARN,

; WEAVING KN!TTING,ETO

FABRIC RELAX WITH WATER 0R STEAM STRETCH FABRIC By their al/omeys United States Patent 3,365,771 METHOD OF MAKING STRETCH YARNS AND FABRICS James E. Brown, Axis, Ala., and William Frank Taylor, Chester, Va., asslgnors to'Courtaulds North America Inc., New York, N.Y., a co oration of Alabama Filed Aug. 26,1965, r. No. 482,831 3 Claims. (Cl. 28-76) This invention relates to a method for making stretch yarns and fabrics from cellulose filaments.

The use of stretchy yarns to make fabrics which have stretch properties has become increasingly widespread. Most of such yarns contain an elastomeric material, either as a component fiber or as an impregnant. The use of elastomns has drawbacks because in many instances they impart an undesirable hand or feel to the fabric and because they add to the cost of the fabric. Moreover, if stretch is imparted to the yarn before it is made into fabric. it becomes diliicult to handle the yarn on conventional textile machinery.

in our copending application Scr. No. 378,275, filed Apr. 28, 1964, there is described a process in which stretch yarns and fabrics can be made from conventional textile grade rayon by treating amulti-ply rayon yarn, specifically a yarn in which at least 65% of the cellulose filaments have a wet modu us less than i g./denier at 5% extension, with a swelling agent equivalent to an aqueous solutioncontaining betwcen'about 5 and about 40% NaOH, and between about 1 and about 8% NaCl, said yarn being treated in the substantial absence of tension. and then applying a reverse twist to the yarn.

The yarns obtained under the conditions described in said prior applicationhave excellent properties, but because the process described requires treatment in the absence of tension, it cannot conveniently be practiced in many types of conventional textile apparatus which inhcrcntly require that the yarn be subjected to tension during processing.

it has now been found that a satisfactory yarn having good stretch properties can be made when the yarn is treated under tension provided that the amount of tension applied is restricted to that which will maintain the yarn at from about 50% to l00% of its original, untreated length or stated another way, which will give a yield. in term of yarn length. of 509610 100%.

The invention therefore includes a method for making a stretchy yarn which comprises treating a yarn having at least two piles and comprising at least 65% by weight regenerated cellulose filaments having a wet modulus of less than 1 g./dcnicr at 5% extension with a swelling agent for cellulose equivalent in swelling effect to an aqueous solution containing between about 5 and about 40% NaOH and between about i and about 8% NaCl. and capable of shrinking said yarn, maintaining said yarn in contact with said swelling agent under tension sufficient to maintain said yarn at at least 50% of its original length and subsequently reverse twisting the treated yarn.

Yarn made in accordance with the invention has an irregular appearance. as will be described more fully below. it may be drawn out and if retained in an extended position for a period of time. will lose its stretchy characteristics. in this condition it may be used on textile machinery like any non-stretch yarn, to make woven or knitted fabrics. Such fabrics upon being wctted out or steamed, without tension, will redevelop the stretch characteristics originally present in the yarn.

The invention therefore further includes a method for making a stretch fabric,which comprises treating a yarn ICC having at least two plies and comprising at least 65% by weight regenerated cellulose fibers having a wet modulus less than 1 g./ denier at 5% extension, with a swelling agent for cellulose equivalent to an aqueous solution containing about 5 and about 40% by weight NaOH and between about i and about 8% by weight NaCl and capable of shrinking said yarn under a tension sufficient to maintain said yarn at at least 50% of its original length, drying the yarn, releasing said tension, reverse twisting the yarn to produce a coiled yarn having an irregular, three-dimensional series of helical sections, pulling out the yarn to form a substantially straight yarn, converting the straight yarn to fabric and relaxing the fabric in an aqueous fluid.

in the drawings:

FIG. 1 is a flow diagram, illustrating the manufacture of stretch yarn in accordance with the invention.

FIG. 2 is a flow diagram illustrating the manufacture of stretch fabric in accordance with the invention.

FIG. 3 is a view in elevation of reverse twisted yarn in accordance with the invention. I

Referring to FIG. l, yarn in accordance with the invention is made by first treating a multi-ply yarn comprising at least 65% regenerated cellulose fiber or filaments having a wet modulus of i g./denier or less at 5% extension with a swelling agent equivalent to an aqueous solution containing 5 to 50% NaOH and 1 to 8% NaCl, under tension sufiicicnt to maintain said yarn at at least 50%, normally 50-l00%, of its original length. There are currently available on the open market several different types of regenerated cellulose. Conven tionai textile grade viscose rayon is characterized by a crenulated surface and a distinct skin-core structure. it may have a conditioned tenacity of say 2.0 to 4 g./deaier and an elongation of say 10 to 30%. it is easily swollen in water and has a very low wet modulus, i.e., when wet a tension of not more than 1 gJdenicr is required to extend it 5%.

Another rayon currently available, though not ordinarily used in textiles, is the tire cord type. This, through the use of viscose modifiers, may have a smooth nonerenulated surface and no detectable skin-core structure. it may have a conditioned tenacity of 4-6 g./denicr and an elongation of say l5 to 25%. Like conventional textile grade rayon, it too is easily swollen in water and has a wet modulus of less than i g./denier at 5% elongation.

Recentlya; new class of rayon has appeared on the market, variously known as polynosique or "high wet modulus rayon. in general it ismadc by spinning unripened viscose into a bath low in regenerative power and then stretching to a high degree. See Tachikawa 2,732,279 and Cox 2,937,070. Such rayons may have conditioned tenacities as high as 7-8 g./denier with extensibilities below 10%. They are characterized by wet moduli of above 1 g./denier at 5% extension.

in our copending application, Scr. No. 474.033 filed July 22, 1965, we have disclosed a method for making stretch yarns and fabrics in which a multi-ply yarn containing at least 65% high wet modulus rayon is subjected I i to a swelling agent equivalent to an aqueous solution containing 5-40% NaOH while under tension suiiicient to maintain said yarn at 50 to of its original length.

As pointed out in that application, solutions of this nature may be applied to high wet modulus rayon without adverse affect, but if applied to conventional rayon (or tire cord type rayon) they gelatlnlze it, breaking down the fiber structure. For this reason, cellulose fiber blends containing more than 35% textile grade rayon cannot be used with the process of our above copending application.

This is a substantial limitation on the use of the process 3 described in said application since the cost of high wet modulus rayon is substantially more than the cost of conventional rayon.

The present process meets this problem by employing a different class of swelling agents, namely those in which a modifying agent is employed to temper the action of the swelling agent. The preferred swelling agent for use in processes according to the present invention is an aqueous solution containing 5 to 40% NaOH and l to 8% NaCl. Equivalent solutions may, however, be made from various combinations of known cellulose swelling agents and salts. Thus, for example, the sodium hydroxide may be replaced by other alkali metal hydroxides and the sodium chloride by other alkali metal salts of strong mineral acids; or alkali metal salts or organic acids having ionization constants (20' C.) of 1.50 or greater.

The multi-ply yarn used in the invention has at least two plies and may have up to say 6 plies. The individual filaments making up the singles yarns may be staple filaments, or continuous filaments.

Yarns employed in the present invention may also include a minor proportion of non-cellnlosic fibers, provided however, that such fibers do not affect the basic nature of the blend.

The singles yarns used in the plied yarn may be of any desired weight or construction varying from about t denier to about 15 denier. They may be twisted in either direction; and to any desired extent. The twist in the component singles yarns, should, however, be opposite in direction to the ply twist. Normally the singles yarns will have l0 to 40 turns per inch and the ply 5 to 40 turns per inch in the opposite direction.

The temperature at which the swelling agent is applied may be varied considerably. in accordance with well known principles, lower temperatures tend to cause a more vigorous swelling action. Conveniently. the treatment is carried out at room temperature (20' C. more or less) but may be carried out at any temperature between the freezing and boiling points of the solution, normally from 0 to 80' C.

The time of treatment will vary depending oathe'.

nature and concentration of the swelling agent and on the nature of the fiber, on the mechanical construction of the yarn and on mechanical details of the treating apparatus. ilroadly, it may range from say 0.! to 120 minutes.

The physical arrangements for treating the yarn may vary widely. in commercial practice aconventionai warp mercerizing machine may be employed. in laboratory or small scale operations, the yarn may be wrapped on a form or bobbin ofsuitabie size and shape, the yarn being wrapped in such a manner that when it undergoes, shrinkage during treatment, it will conform to theoutiine of the form or bobbin and thus reach the desired proporteristics. When, however, the resulting fabric is wetted, Q or steamed, under zero tension, the stretch characteristic redevelops and the result is a stretch fabric made of 100% cellulose.

This sequence is illustrated schematically in FIG. 2. The invention will be further described in the following examples.

Example 1 Samples of a 30/2 (5.5 TM) conventional textile grade rayon yarn having a wet modulus of .35 at 5% extension are wrapped on plastic forms in such a way that when shrunk to conform to the forms they have lengths 50, 70, 80, 90, 95 and 100% of the original length. They are then treated with 20% aqueous NaOH, and aqueous solution containing 20% NaOH and 4% NaCl for 2 minutes at 20' C. All samples shrink to fit closely over the forms. The samples are washed with water at 60 C., neutralized with 5% acetic acid, washed with water and dried on the forms. They are then removed from the forms and reverse twisted to 3L8 turns per inch. Samples of the reverse twisted yarn are then relaxed in water for 30 minutes at 60 C. and dried. Recovery values are determined by stretching samples of the yarn along a calibrated scale tion of its original length and so be subjected to the appropriate tension. The treating liquor may be applied by dipping, spraying or in any other convenient way.

Following contact with the swelling agent the yarn' is washed, neutralized with a weak acid such as acetic acid, and dried. These steps are carried out with the yarn under tension.

in accordance with the invention, the yarn is then reverse twisted, i.e., it is given a twist in a direction opposiie to that in which it was plied. While the degree of reverse twist may vary, preferably it is between about 135 and 160% of the initial ply twist. The result is shown clearly in FIG. 3. As can be seen from that figure, the yarn is now an irregular three-dimensional sequence of helical sections, the helix angle of succeeding sections varying in an arbltraryand random manner. The yarn is stretchy and when extended and released wlll'recover its original length to a high degree.

it is difllettlt to process stretch yarn, as such, on looms and knitting machines, precisely because it is stretch yarn. However, this is not a problem with the present yarn because when the yarn is wound on a spool, preparatory to maximum usable stretch, or of maximum usable stretch. as the case may be, keeping the yarns at that point for 5 minutes and then relaxing for 1 minute before noting the return length. The results are as follows:

Shrinkage Maximum Recovery During Usable Recoverv from 60% of Sample Treatment Stretch (percent Maximum (percent) (percent) Usuhlo Stretch A 60 123 M ll 30 121 38 K3 C '20 120 30 ti) D l0 ll!) 44 83 i: 6 [Oil 3t! H2 F. 0 U8 4!: 8i

in these results, percent recovery is calculated as follows:

percent stretch X100 Percent recoverywhere Percent strateh- X 100 winding, the yarn is knitted into a fabric which is relaxed in water at C. for 5 minutes. it has excellent stretch and recovery characteristics.

What is claimed is: I

l. A method for making a stretchy yarn which comprises contacting a textile grade regenerated Cellulose yarn having at least 2 piles with a cellulose swelling agent equivalent to an aqueous solution containing 5 'to 40% sodium hydroxide and l to 8% NaCl, and capable of shrinking said yarn, maintaining said yarn during contact with said swelling agent under a tension sufficient to maintain said yarn at at least of original length and subsequently reverse twisting the treated yarn in a direction opposite to the initial ply twist and to a degree greater than the initial ply twist.

2. A method for making a stretch yarn which comrises treating a plied yarn consisting essentially of rayon filaments having a wet modulus less than about 1 gram per denier at 5% extension, with an aqueous solution containing 5 to 40% by weight NaOH and 1 to 8% NaCl,

at a temperature between about 0 and about 80 C., for between about 0.1 and about minutes, and rnaintainprises treating a multi-ply yarn consisting essentially of converting theyarn'to a fabric and relaxing the fabric in an aqueous fluid.

References Cited UNITED STATES PATENTS 1,392,833 10/1921 Jones et a1. 8 1,591,922 7/1926 Hans 8-433 X 1,758,553 5/1930 Bassett et al. 8-133 X 1,765,581, 6/1930 Hall 8-133 2,497,519 2/1950 Stevenson et al 8-125 2,254,740 9/1941 Hansen et a1 57-139 2,463,618 3/1949 Heberlein et a]. 57157 2,895,287 7/ 1959 Yoo 57164 2,895,288 7/ 1959 Yoo 57-164 FOREIGN PATENTS 501,833 1939 Great Britain.

OTHER REFERENCES Some Fundamentals of Stretch Cottons, by E. S. Olson; American Dyestutf Reporter, vol. 52; No. 18; Sept. 2, 1963, pp. 21-8, 52.

LOUIS K. Rumour, Primary Eqraminer. 

1. A METHOD FOR MAKING A STRETCHY YARN WHICH COMPRISES CONTACTING A TEXTILE GRADE REGENERATED CELLULOSE YARN HAVING AT LEAST 2 PLIES WITH A CELLULOSE SWELLING AGENT EQUIVALENT TO AN AQUEOUS SOLUTION CONTAINING 5 TO 40% SODIUM HYDROXIDE AND 1 AND 8% NACL, AND CAPABLE OF SHRINKING SAID YARN, MAINTAINING SAID YARN DURING CONTACT WITH SAID SWELLING AGENT UNDER A TENSION SUFFICIENT TO MAINTAIN SAID YARN AT AT LEAST 50% OF ITS ORIGINAL LENGTH AND SUBSEQUENTLY REVERSE TWISTING THE TREATED YARN IN A DIRECTION OPPOSITE TO THE INITIAL PLY TWIST AND TO A DEGREE GREATER THAN THE INITIAL PLY TWIST. 